A subscriber identification module (SIM) is an integrated circuit, typically embedded into a SIM card, which securely stores network-specific information used to authenticate and identify subscribers on the network, the network typically corresponding to a mobile/cellular telephone network. The most important information stored on the SIM includes the International Mobile Subscriber Identity (IMSI), which is used to identify a SIM card with respect to its individual operator network, the SIM's unique international circuit card identifier (ICCID) and an authentication key (Ki) used to identify and authenticate subscribers on mobile stations (such as cellular/mobile telephones and computers, although the phrase “mobile station” will generally be used in the specification to refer to such devices).
The IMSI number in turn typically comprises one or more of the following:                a mobile country code (MCC), in terms of which use of the mobile station will be limited to one country;        a mobile network code (MNC), in terms of which use of the mobile station will be limited to a pre-determined network, such as Orange or Vodafone, for example; and        a mobile station identification number (MSIN) in terms of which use of the mobile station will be limited to one SIM card.        
The IMSI is also used to acquire other details of the mobile station in a Home Location Register (HLR) or as locally copied in a Visitor Location Register (VLR). The HLR is a central database that contains details of each mobile station subscriber that is authorized to use the GSM core network. The VLR is a database of the subscribers who have roamed into the jurisdiction of the MSC (Mobile Switching Center) which it serves. Each base station in the network is served by exactly one VLR, hence a subscriber cannot be present in more than one VLR at a time. The data stored in the VLR has either been received from the HLR, or collected from the mobile station. Whenever a new mobile station is detected on its network, the operator not only creates a new record in its VLR, but it also updates the HLR of the mobile subscriber, apprising it of the new location of that mobile station.
The Ki authentication key is a 128-bit value used in authenticating the SIMs on a mobile network. Each SIM holds a unique Ki assigned to it by the operator during a personalization process. The Ki is also stored in a database on the carrier's network.
The SIM card provides a software function that allows the mobile station to pass data to the SIM card to be signed with the Ki. This, by design, makes usage of the SIM card mandatory unless the Ki can be extracted from the SIM card.
Turning now to FIG. 1, the typical authentication process, to enable a mobile station (MS) 1 to connect to a network 5, will be described. However, before doing so, at a high level and in respect of one aspect of the mobile station 1, the mobile station 1 comprises a baseband processor 2 to manage the antenna-related functions of the mobile station 1 and a SIM card 3, with the baseband processor 2 communicating with the network 5. The SIM card 3 in turn comprises a baseband only component 3.1 that can communicate with the network 5 via the baseband processor 2. The SIM card 3 further comprises a memory component 3.2. The mobile station 1 further comprises an application layer 4 to run software required to operate the mobile station 1.
With this in mind, the authentication process comprises the following steps:                1. When the mobile station 1 starts up, the application layer 4 request a connection from the baseband processor 2.        2. The baseband processor 2 then requests the mobile station's International Mobile Equipment Identity (IMEI) number, which uniquely identifies the mobile station 1, from the SIM card 3, as well as the IMSI, which then gets sent as part of a connection/authentication request to the network 5. The mobile station may have to pass a PIN to the SIM card 3 before the SIM card 3 will reveal this information.        3. The operator network searches its database for the incoming IMSI and its associated Ki.        4. The operator network then generates a Random Number (RAND) based on the predefined Ki, and from this it generates an authentication vector 1 (AV1).        5. The operator network then sends the RAND to the mobile station 1. The mobile station 1 then uses its predefined Ki (which should match the Ki used by the network operator) and the RAND to generate an authentication vector 2 (AV2). The mobile station 1 then passes the AV2 back to the network operator.        6. The operator network then compares AV1 and AV2, and if there is a match, mobile station 1 is granted access to the operator's network 5.        
As briefly touched on above, in order to extend the connectivity service of a mobile station to a location that is different from the home location where the service was registered, the mobile station needs to undergo a roaming process. In terms of a conventional roaming process, when the mobile station is turned on or is transferred via a handover to a new network, this new “visited” network sees the mobile station, notices that it is not registered with its own system, and attempts to identify its home network. The visited network then contacts the home network and requests service information (including whether or not the mobile station should be allowed to roam) about the roaming mobile station using the IMSI number.
If successful, the visited network begins to maintain a temporary subscriber record for the mobile station. Likewise, the home network updates its information to indicate that the mobile station is on the host network so that any information sent to that mobile station can be correctly routed.
In terms of the above, it will be appreciated that the annual revenue of the cellular industry worldwide, with regard to the provision of roaming service, is estimated at well over 12 billion dollars. In this regard, income generated through roaming charges is incurred by end users making or receiving calls, data or text messages outside of their home network. In some countries networks allow users to roam anywhere in the country and not incur any surcharges for using their mobile stations. In other countries, like Canada, simply leaving the metropolitan area that you reside in can result in roaming charges being incurred. However, in almost all cases leaving the country you reside in will result in excessive roaming charges being incurred.
Turning now to the issue of interconnect charges (i.e. fees billed to a given network to terminate a call on another network), these generally represent a major barrier to entry for new market participants. Newly established networks face high interconnect charges as a result of having a relatively small market share when compared to incumbent networks. Outgoing calls from the new network's consumers are more than likely to be terminated on a competitor's network. Many of these networks must offer free incoming calls in order to attract consumers, as free incoming calls have been the de facto standard for many years. Thus, revenue is only earned when subscribers make outgoing calls. The new networks are thus under pressure, since to attract new customers these new customers must invariably switch from an incumbent network that is already offering relatively low outgoing rates (and which the incumbent network would naturally try to protect since this represents their only source of revenue).
Most networks also offer a lower rate for intra-network calls (as opposed to inter-network calls, as described in the previous paragraph) i.e. calls between subscribers on the same network, since these calls do not necessitate the need to pay interconnect fees. To take advantage of this (and thus, to a certain extent, to reduce the paying of interconnect fees), consumers carry multiple SIM cards so that people wishing to contact them always do so without having to make inter-network calls.
All of the above makes it exceedingly difficult to switch to a new provider or network and hence for new providers and networks to attract new customers. In addition, customers who have a prepaid plan with a new network still retain the SIM cards of the incumbent network. In view of cost fluctuations in the price of minutes, the availability of minutes at a given retailer or other factors, consumers are less likely to consistently purchase new minutes on the new network. In addition, users cannot simply forward their calls to the new network's SIM/number without incurring a call forwarding cost.
Of further relevance to the context of the present invention, are so-called mobile virtual network operators. A mobile virtual network operator (MVNO) is a wireless communications services provider that does not own the radio spectrum or wireless network infrastructure over which the MVNO provides services to its customers. An MVNO enters into a business agreement with a mobile network operator to obtain bulk access to network services at wholesale rates, and then sets retail prices independently. An MVNO may use its own customer service and billing support systems and its own customer service, marketing and sales personnel. The MVNO business model is one in which no significant capital expenditure on spectrum and infrastructure is incurred. In addition, MVNOs do not have the time-consuming task of building out extensive radio infrastructure. The relevance of MVNOs to the present invention will become clearer further on in the specification.
MVNOs may be classified as either a reseller MVNO or a Full Infrastructure MVNO, with the former simply being a branding entity with neither its own mobile licence or its own mobile infrastructure, whilst the latter does indeed have its own mobile licence and/or mobile infrastructure. In both cases, the MVNO has the direct customer relationship with the end user. The MVNO is able to handle Network Routing themselves and will typically have entered into roaming deals with foreign MNOs. The MVNO is often able to produce and distribute for example voice minutes and data traffic, typically by tagging onto their existing fixed line operation, and the MVNO will typically be able to handle producing SMS and MMS messages. A typical MVNO will be able to handle customer service, customer billing and collection of consumption data and handset management. Furthermore the MVNO will usually handle marketing and sales to end-users themselves.